Ignition device for explosion engines

ABSTRACT

An electrical ignition device for explosion engines of the type with a low ohmic resistance of the primary winding and a resistor in series with this winding. A discharge condenser acts on opening of the primary circuit in which the condenser is connected, directly or indirectly, between earth and an intermediate point in the circuit formed by the resistor and primary winding, thereby excluding the resistor from the circuit during the discharge stage.

United States Patent Jan. 28,1975

Fazzo l5 l lGNlTlON DEVICE FOR EXPLOSION 3.581,?25 6/l97l Hemphill .1l23/l48 E ENGINES [76] Inventor: Vincenzo Fazzo, Via Albani 7, 'f 'f 'll Myhre Milan Italy 20149 Avm'la/zr [:xummefi-Ronbld B. Cox

Attorney Agent, or Firm-Guido Modiano; Albert [22] Filed: Sept. 29, I972.losii [21] Appl. No.: 293,741

1 [57] ABSTRACT [52] [1,5, (,l, H 123/148 [)(j, 123/148 3 An electricalignition device for explosion engines of 1511 1111.01. F02p 1/00 the ypwith a low Ohmic resistance of the p y 15g i ,1 S 123/143 g 141; AC, 43DC winding and a resistor in series with this winding.

l B A discharge condenser acts on opening of the primary circuit inwhich the condenser is connected directly Reference-S Cited orindirectly, between earth and an intermediate point UNITED STATESPATENTS in the circuit formed by the resistor and primary 3 1125 43113/1962 Leppala... l23/l48 E Winding thereby excluding the resistor fmm3.217.216 ll/l965 D0110 123/148 E Circuit during the discharge Stage-3.34().86l 9/1967 Schiff l23/l48 E 3.550.573 12/1970 Kowalski 123/]48 E3 l Drawmg 1 IGNITION DEVICE FOR EXPLOSION ENGINES BACKGROUND OF THEINVENTION The present invention relates to an electrical ignition devicefor explosion engines, of thecoil ignition type.

Ignition devices of the coil ignition type commonly used inexplosionengines comprise the use of a primary winding with a fewturns'which is magnetically linked with a secondary winding with a muchlarger number of turns. The primary winding is connected at one end tothe source of energy (for example the battery) and at the other end itis connected to earthby way of a switch or contact breaker which iscyclically controlled so that it opens and closes in phase with theengine cycle. In addition, a condenser is connected in parallel withthis switch. In its turn the secondary of the coil is connected at oneend directly or indirectly to the I sparking plugs'of the engine, and atthe other end is fed by the battery.

The operation of these devices is well known in the art and does notrequire illustration. It is sufficientto note that during each cycle,when the switch or circuit breaker connecting the primary to earth isclosed, the current flows in theprimary without concerning thecondenser. i

However, when the primary circuit is opened at the switch, the condensercharges and then discharges through the primary, to create the knownelectromagnetic phenomena which lead to the formation of the spark atthe sparking plugs.

As the current in the primary winding, subjected to the constantavailable voltage, could reach excessive values when the engine is atrest with the key inserted, or when it rotates slowly (in that the timeavailable for the establishment of the current is in this case greater)it isnecessary for the ohmic resistance of the primary circuit to besuitably sized, both to avoid excessive heating of the coil and so asnot to overload the switch contacts.

This is the reason that in those coils at present available which have alow ohmic resistance (and give better performance) there is a resistorconnected in series, which constitutes a barrier against excessiveincrease in the charging current.

This separation of function hence enables the resistor to be mountedexternal to the coil casing, so favouring dissipation of heat. Devicesconstructed up to the pres- SUMMARY OF THE INVENTION The presentinvention proposes to obviate these disadvantages by providing anelectrical ignition device of a new type, which because of its improvedsolution to the problem gives aconsiderable reduction in losses at theresistor, specifically during the discharge cycles, thus leading to anincrease in the efficiency of the device with respect to traditionaldevices.

A further object of the invention is that said improved devicefacilitates and renders more convenient the use of resistors of aparticular type, so as to give spark characteristics which are moresatisfactory and substantially constant over a wide range of enginespeeds.

A further object of the invention is that the device according to theinvention gives unexceptionable operation for any engine speed, i.e.,both at low and high engine speed, and does not require mechanical orelectro mechanical intervention members for adaptation to the enginespeed.

These and further objects are attained by an electrical ignition devicefor explosion engines, of the type with a low ohmic resistance of theprimary winding and a resistor in series with this winding, and with adischarge condenser acting on opening of the primary circuit, in whichsaid condenser is connected, directly or indirectly, between earth andan intermediate point in the circuit formed by the resistor and primarywinding, so as to exclude said resistor from the circuit during thedischarge stage.

BRIEF DESCRIPTION OF THE DRAWING Further characteristics and advantageswill be more evident from the description of an ignition deviceaccording to the invention, a preferred but not exclusive embodiment ofthe electrical schematic diagram of which is shown in the single FIGUREin the accompanying drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENT In this drawing the primarywinding (with a few turns) and secondary winding (with a large number ofturns) of the ignition coil are indicated by the reference numerals 1and 2. Both theprimary and secondary are connected, in known manner byway of the conductor 3, to the battery 4. The secondary is connected inknown manner by way of the conductor 5 to the single sparking plug or tothe sparking plug ignition distributor 6, connected to earth at 7. Asthe primary winding 1 is of low ohmic resistance, it is connected inseries with a resistor 8, preferably non-inductive, having an ohmicresistance of such a value as to limit the intensity of the chargingcurrent which traverses the primary 1 when it is fed by the battery(switch closed) to the required value. The switch of this circuit isindicated diagrammatically by the reference numeral 9, and connects theresistor 8 to earth 7.

The circuit is new in that it comprises the connection of a dischargecondenser 10 between the earth 7 and an intermediate point 1 1 betweenthe resistor 8 and primary 1.

The connection of the discharge condenser 10 in this position leads toreally surprising and notable results. Whereas, as is usual, thecondenser 10 is practically inert when the primary 1 is fed by thebattery, because the circuit is closed by the circuit breaker 9, ithowever acts when the circuit is broken at 9. charging and successivelydischarging through the winding 1, without the alternating currenttraversing the resistor 8. It follows that during discharge the primarycircuit has a lower resistance (caused by the exclusion of the resistorfrom the circuit during this stage), because of which a superior andbetter utilisation of the energy stored by this circuit during chargingis obtained. The resistance losses due to the element 8 are in facteliminated. This different degree of conductivity of the circuit betweenthe charging and discharging stages exists for any engine speed and isproduced not by mechanical means (such as switches which connect ordisconnect resistare used, because this requires larger supplementaryresistors (for the already stated requirement of limiting the chargingcurrent), Moreover, the fact of having separated the resistor 8 from thedischarge currents facilitates and renders more convenient the use ofresistors having particular characteristics (for example, resistors withpositive temperature coefficients to ensure the constancy of thedischarge tension as the motor speed varies).

I Evidently the invention so conceived is susceptible to numerousmodifications all of which fall within the scope of the inventive idea.Thus, it is possible within the inventive idea to connect a resistor ofsuitablevalue in parallel with the contacts of the circuit breaker 9 forreducing the voltage across the contacts during their opening. Acondenser'may beseries connected to the resistor, this assembly thusdefining a means for reducing overtension upon opening of the circuitbreaker 9. lclaim:

1. An electrical ignitiondevice for explosion engines comprising anignition coil including a primary and a secondary winding circuits, asourceof electrical current connected toat least one of said windingcircuits,

a sparking plug branch connected with said secondary circuit, circuitbreaker means -in series with said primary winding circuit, a resistorin series with said primary winding circuit and a condenser directlyconnected between the point of connection of said primary windingcircuit with said resistor and the ground, said the source of electricalcurrent has one pole thereof V breaker means.

grounded, said condenser has i one plate thereof grounded and saidcircuit breaker has one end thereof groundedr V 3. An electricalignition device for explosion engines as claimed in claim vl, furthercomprising in parallel with said circuit breaker means a furtherresistor in 'se ties with a further condenser for reducing overtensionoccurring upon opening of the contacts of said circuit with said primarywinding

1. An electrical ignition device for explosion engines comprising anignition coil including a primary and a secondary winding circuits, asource of electrical current connected to at least one of said windingcircuits, a sparking plug branch connected with said secondary circuit,circuit breaker means in series with said primary winding circuit, aresistor in series with said primary winding circuit and a condenserdirectly connected between the point of connection of said primarywinding circuit with said resistor and the ground, said primary windingcircuit being of the type in which the primary winding circuit has a lowohmic resistance, and wherein, according to the improvement, saidresistor is arranged in series with said primary winding circuit betweensaid circuit breaker means and the point of connection of said condenserwith said primary winding circuit.
 2. An ignition device according toclaim 1, wherein the source of electrical current has one pole thereofgrounded, said condenser has one plate thereof grounded and said circuitbreaker has one end thereof grounded.
 3. An electrical ignition devicefor explosion engines as claimed in claim 1, further comprising inparallel with said circuit breaker means a further resistor in serieswith a further condenser for reducing overtension occurring upon openingof the contacts of said circuit breaker means.